The present invention relates to an amphibious vehicle having a single driving engine which may power a travel drive and a swim drive simultaneously or independently of one another by choice.
Motor vehicles of the most varied type are being increasingly used in the leisure-time sector for pleasure purposes. Examples of this are snowmobiles, jet skis or even dune buggies which are constructed with three or four balloon tires and therefore are able to move in sand, as well. Disadvantageous in such vehicles is that, in each case, they are only usable in one environment, or else are not suitable for pleasure purposes. Examples for this are snow cats or amphibious vehicles. Amphibious vehicles for military or civil purposes are relatively large and unwieldy. The reason for this is mainly that the bottom side of the motor vehicle is modeled after a boat hull to ensure the ability to float. In other type models, the attempt is being made to improve the buoyancy of conventional motor vehicles by modifications such as float outriggers, the water speeds attainable thereby remaining unsatisfactory.
German Published Patent Application No. 35 22 041 describes an all-wheel-drive amphibious vehicle having high water-travel speed, in which, by arranging a paddle and baffle-plate system at all four wheels, strong buoyancy forces are produced during water travel which lift the vehicle body out of the water. Only the wheels with the paddles remain in contact with the water. Since the particularly high resistance in water, otherwise inherent in the shape of amphibious vehicles, thereby ceases to exist, the propulsion forces likewise produced by the paddle system can lend to the vehicle the high water-travel speed demanded. The paddles of the system with their mount fixtures are detachably arranged on the wheels, and must be detached for land travel and installed prior to swim operation. Alternatively, it is proposed to join the wheels and the paddle system permanently to one another. Disadvantageous in the amphibious vehicles, depending on the model type, is either the cumbersome assembly and disassembly, respectively, or the high costs for an automatic insertion and ejection device for the paddle system.
German Published Patent Application No. 38 32 559 describes an amphibious motor vehicle having an engine which powers a water drive directly, and powers a land drive via a gear. Inserted in the drive train of the land drive is a clutch, the coupling force of which during landing and leaving the water is variable in accordance with the difference between the actual speed and the setpoint speed of the land drive in such a way that the drive speed is regulable in a controlled manner up to the setpoint speed. In this manner, the driving engine of the amphibious motor vehicle can be run with full speed even during landing, so that the water drive, which can be constructed as a screw or jet, supplies the maximum thrust for supporting the landing and the exit from the water.
German Published Patent Application No. 39 16 200 describes a drive system for an amphibious vehicle in which only a single driving engine is necessary, and nevertheless, the travel drive and the swim drive can be operated simultaneously or independently of one another by choice. In this manner, it is possible that, given simultaneous operation of the travel drive and the swim drive using only one driving engine, and preferably at constant engine speed, the travel drive train and the swim drive train are controllable or regulable independently of one another with respect to speed and output. In particular, this is of great advantage during landing (transition from water to land) and leaving land (transition from land into the water), so that, for example, the wheels of the amphibious vehicle do not dig into the soft ground of the shore. A single travel drive train is sufficient for the travel drive, and a single swim drive train is sufficient for the swim drive. If the amphibious vehicle has a plurality of swim propulsion devices, e.g., several propellers or several hydrojets, it is then advantageous if each of these swim propulsion devices has its own swim drive train, which are controllable or regulable jointly or independently of one another by choice.
Therefore, it is an object of the present invention to provide an off-road amphibious vehicle particularly for free-time purposes, which is switchable from normal driving operation to swim operation with minimal expenditure, allows sufficiently great speeds in both operating modes, and permits an open seating position of the motor-vehicle driver.
Due to the central arrangement of the driving engine, the center of gravity of the amphibious vehicle may be shifted in the direction of the buoyancy point, such that the center of gravity of the vehicle in the known state is located above the buoyancy point, so that essentially no moments of rotation occur. Despite the open seating arrangement, the amphibious vehicle thereby maintains a stable water position which for the first time permits a meaningful water operation. Due to the all-wheel drive, the amphibious vehicle has full off-road capability. On one hand, the swim drive, configured as a jet drive, may ensure sufficient water speeds, and secondly, in contrast to a screw, may not be so easily damaged in normal driving operation, as well as representing no injury risk for a third party.
In an example embodiment, the tires of the amphibious vehicle may be constructed as balloon tires which, on one hand, are of benefit to the normal driving operation in sand, and secondly, act simultaneously as buoyancy bodies during swim operation, the rear balloon tires, for example, being somewhat larger than the front balloon tires for the normal driving operation.
Furthermore, to improve the buoyancy, additional discrete buoyancy bodies, e.g., constructed as air tanks, may be provided in the front and/or rear region of the amphibious vehicle. Moreover, the buoyancy point may be better adjusted with the aid of these discrete buoyancy bodies, which may be detachable.